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 $ @LastEditTime: 2022-06-12 10:54:59
 $ @FilePath: \st-html.github.io\src\aaa011\a062背景色.html
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 $ @Author: liujiajun 45444154+wo1261931780@users.noreply.github.com
 $ @Date: 2022-06-11 22:30:24
 $ @LastEditors: liujiajun 45444154+wo1261931780@users.noreply.github.com
 $ @LastEditTime: 2022-06-11 22:30:29
 $ @FilePath: \st-html.github.io\src\aaa011\a062背景色.html
 $ @Description: 1111
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 $ @Copyright (c) 2022 by liujiajun 45444154+wo1261931780@users.noreply.github.com, All Rights Reserved.
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<!DOCTYPE html>
<html lang="en">

    <head>
        <meta charset="UTF-8">
        <meta http-equiv="X-UA-Compatible"
              content="IE=edge">
        <meta name="viewport"
              content="width=device-width, initial-scale=1.0">
        <title>Document</title>
        <style>
            div {
                width: 300px;
                height: 300px;
                text-align: center;
                /* background-color: #ccc; */
                /* background-color: rgba(16, 122, 195, 0.5); */
                /* 0.5表示50%的透明度 */
                /* background-color: rgba(16, 122, 195, 0.9); */
                /* 0.9表示90%透明度 */
                /* 数值越大，透明度越低，透视能力越差 */
                background-color: rgba(16, 122, 195, .9);
                /* 可以直接省略0，效果一样 */
            }
        </style>
    </head>

    <body>
        <div>我是背景色</div>
        <!-- 如果一个标签，没有事先说明背景颜色，那么默认是透明的 -->
        <!-- transparent=0 -->

    </body>

</html>